A Retrospective Study of Mucopolysaccharidosis Type II in Brazil - Data from Brazilian Health System (DATASUS)

Abstract Data on Mucopolysaccharidosis type II (MPS II) in Latin America are scarce. This retrospective database study, using data from the Informatics Department of the Brazilian Health System (DATASUS), aimed to estimate the prevalence of MPSII in Brazil from 2008 to 2020 and to describe demographic and clinical profiles from patients under treatment. The study population was derived from DATASUS records of MPS II (ICD-10 E76.1) diagnosed in Brazil. Initially 455 patients were found, but only 181 patients who were receiving idursulfase treatment were included in this study. Among these cases, as expected in a X-linked disease, all were males and 40% of the cases were recorded in the Southeast region, and another 34% in the Northeast region. The biggest proportion of patients (39%) were diagnosed when they were 10-19 years old. There are 212 clinical conditions associated with MPS II, although the main comorbidities related to MPSII include: abdominal/inguinal hernia, respiratory complications, and carpal tunnel syndrome. Respiratory disorders were the fifth most frequent comorbidity recorded in these patients. The healthcare professionals in Brazil more involved in the diagnosis of MPS II were radiologists, followed by geneticists and cardiologists. Despite some limitations, DATASUS is a relevant database to provide information on rare diseases such as MPS II. Most cases were reported in southeast and northeast regions, respectively. This information is crucial to help design targeted public policies.

Evaluation of impact of anti-idursulfase antibodies during long-term idursulfase enzyme replacement therapy in mucopolysaccharidosis II patients.

OBJECTIVES: This 109-week, nonrandomized, observational study of mucopolysaccharidosis II (MPS II) patients already enrolled in the Hunter Outcome Survey (HOS) (NCT00882921), assessed the long-term immunogenicity of idursulfase, and examined the effect of idursulfase-specific antibody generation on treatment safety (via infusion-related adverse events [IRAEs]) and pharmacodynamics (via urinary glycosaminoglycans [uGAGs]). METHODS: Male patients ≥ 5 years, enrolled in HOS regardless of idursulfase treatment status were eligible. Blood/urine samples for anti-idursulfase antibody testing and uGAG measurement were collected every 12 weeks. RESULTS: Due to difficulties in enrolling treatment-naïve patients, data collection was limited to 26 enrolled patients of 100 planned patients (aged 5.1-35.5 years) all of whom were non-naïve to treatment. Fifteen (58%) patients completed the study. There were 11/26 (42%) seropositive patients at baseline (Ab +), and 2/26 (8%) others developed intermittent seropositivity by Week 13. A total of 9/26 patients (35%) had ≥ 1 sample positive for neutralizing antibodies. Baseline uGAG levels were low due to prior idursulfase treatment and did not change appreciably thereafter. Ab + patients had persistently higher uGAG levels at entry and throughout the study than Ab - patients. Nine of 26 (34%) patients reported IRAEs. Ab + patients appeared to have a higher risk of developing IRAEs than Ab - patients. However, the relative risk was not statistically significant and decreased after adjustment for age. CONCLUSIONS: 50% of study patients developed idursulfase antibodies. Notably Ab + patients had persistently higher average uGAG levels. A clear association between IRAEs and antibodies was not established.

Wide allelic heterogeneity with predominance of large IDS gene complex rearrangements in a sample of Mexican patients with Hunter syndrome.

Hunter syndrome or mucopolysaccharidosis type II (MPSII) is caused by pathogenic variants in the IDS gene. This is the first study that examines the mutational spectrum in 25 unrelated Mexican MPSII families. The responsible genotype was identified in 96% of the families (24/25) with 10 novel pathogenic variants: c.133G>C, c.1003C>T, c.1025A>C, c.463_464delinsCCGTATAGCTGG, c.754_767del, c.1132_1133del, c.1463del, c.508-1G>C, c.1006+1G>T and c.(-217_103del). Extensive IDS gene deletions were identified in four patients; using DNA microarray analysis two patients showed the loss of the entire AFF2 gene, and epilepsy developed in only one of them. Wide allelic heterogeneity was noted, with large gene alterations (e.g. IDS/IDSP1 gene inversions, partial to extensive IDS deletions, and one chimeric IDS-IDSP1 allele) that occurred at higher frequencies than previously reported (36% vs 18.9-29%). The frequency of carrier mothers (80%) is consistent with previous descriptions (>70%). Carrier assignment allowed molecular prenatal diagnoses. Notably, somatic and germline mosaicism was identified in one family, and two patients presented thrombocytopenic purpura and pancytopenia after idursulfase enzyme replacement treatment. Our findings suggest a wide allelic heterogeneity in Mexican MPSII patients; DNA microarray analysis contributes to further delineation of the resulting phenotype for IDS and neighboring loci deletions.